Production of pyridines



a from. the following. detailed Patented July 15, 1952 raonuo rron F PYRIDINESJ.

an Hoog andfWiIIem Frederik dam, Netherlands, assignors to Shell Develop- Engel, Ar'nstermerit CompanygS'an Francisco, Calif., a corporation of Delaware No Drawing. Application .lune 9, 1947,

753,576. A In theNetherlands February 23,

Serial No.

Section 1, Public Law 690, August 8, 1946 Patentexpir'es February 23, 1964 This invention relates tothe production of unsaturated cyclic nitrogen compounds contain ing a six-membered monoheteroatomic ring in which the heteroatom is nitrogen. The invention relates more particularly to the production of alkyl pyridines. A particular aspect of the invention relates to the production of betapicoline.

The unsaturated cyclic nitrogen compounds containing nitrogen in the ring, such as the alkyl pyridines, are valuable as starting or intermediate materials inrthe production of a wide variety of products comprising dyes, pharmaceuticals and many other chemical derivatives. Thus 3-methyl pyridine (beta-picoline) isthe starting material for such valuable chemical derivatives as nicotinic acid. Methodsdisclosed heretofore for the productionof these organic nitrogen compounds are often handicapped by difli-- culties rendering impractical their utilizationon a large scale. Such difiiculties comprise, for example,'the production of the specific monoheteroatomic cyclic nitrogen compound as a component of a reaction mixture fromwhich its separation in a high state of purity is often exceedingly difficult. Further disadvantages of many such processes disclosed heretofore reside in therela- Vtively low yields of the desired cyclic nitrogen compound often encountered. ,A- still further disadvantage resides in the reliance upon starting material which is often ,not irmnediat'ely available or not readily available ata cost commensu'rate, with practical application of .the

process-I v y .'It. is an object of the present invention to obviate the above improved process'for the more efiicient production of, unsaturated cyclic nitrogen compounds having a 'six-membered monoheteroatomic ring in which therheteroatom is nitrogen.

, .It is a further pounds comprising alkyl pyridines.

I of methylpyridines (picclines) fromreadily available, starting material.

production f t i li allQu et, c i'e ssa advantages of the invention will become apparent description thereof.

-,The objectsand advantages Qf- "h8 present on-are; 9bta ed.. ;by cpnta ina; n ;-u

difiiculties and to provide an bject of, the invention to. ro-" ide an improved process j for the, more 'efiicient production of unsaturated cyclic nitrogen com- -,A still firther'. object of. the invention isthe provision-lot an improved process for the more eflicient production SQQIaims. (01. 260-4590) need .not necessarily consist saturated aliphatic alcohol in admixture with ammonia or an aliphatic amine at a temperature in the range of from about 300 C. to about 500 -C.' with a suitable catalytic material defined more fully below.

Suitable aliphatic unsaturated alcohols which are employed as starting material intheprocess of the invention comprise the beta, gammaoleflnic alcohols. By the term, beta, gammaolefinic alcohols used in the present specification and attached claims, is meant the; class-of unsaturated alcohols having an -olefinic, double bonded-linkage between two carbon atoms which are in the beta andgamma position-with respect to the saturated carbon atom to, which the hydroxyl group ofthe alcohol is directly attached. In other words, the class of unsaturated alcohols utilized as charged to'the process of the invention :has an olefinic linkage between of which; is linked; to a having the: OH' group The lowest-member of alcohol charge to the system of only asingle unsaturated alcohol of the defined class, but maycomprisega mixture of two or more; such alcohols. The unsaturated ,alcoholoharge may furthermore comprise lesser-amounts of other hydrocarbons capable or, not of; :undergoingconversion under, the reaction conditions -but in- The unsaturated capable of undergoing reaction with the reactants -.or-- otherwise unfavorably influencing the process '1 under the operating conditions employed, a

ammonia is preferred asthe Ammonia, gases comprising ammonia, or compounds giving rise toammoniaunderpthereaction conditions, obtained.;from any" suitable -;source is combined with-the;unsaturated aliphatic alcohol chargepor is separately introduced into the --reaction gene; 1 Althou h the use; of

reactant -,providing the nitrogen atom, ammonia may ice-replaced in part or in its entirety with an aliphatic amine within the scope "of; the invention.- 9 Suitable ialiphaticramines which may be employed v comv prise for, example methylarmine, ethylamine npropylamine, isopropylamine, dimethylamine, di-

xet m e; d ro vlam n bu }aminai-.; Q-- 'butylamine, the dibutylamines, theamylagni ,es, 1

the dihexylamines; -methylpropylam1ne,' methylbutylamine, ethylbutylamine, propylamylamine,

- cyclopentylamine -urnethylcyclopentylamine, oy-

clohexylamines, andthe like. lf desired mpre a o sueh, a .v y e cha e wi 1 the: catalyst.

aimylamine, sec-butylamine, i'soamylamine, the hexylamines, and the like.

The introduction of ammonia and/or aminef, 1i

into the system is preferably controlledto main-L mm at least one mol of ammonia or amine'per mol of alcohol in the reaction zone-c It;gis--pre.-- ferred to maintain a molratio of ammon-ia or amine to unsaturated alcohol'chargeiiof' fromi about 1 to about 15, and preferably from about 3 to about 10. It is to be understood however, that the amount of ammonia introducediinto the system may vary to some degree from the above limits within the scope of the i'nvention Diluents, comprising for example nitrogen, or

steam, may be mixed with the alcoholand/or ammonia and/or aminacharge, or may be sepa-' rately introduced into'the reaction zone at one or more points along the length thereof. Diluents"such as, for examplenitrogen, are suit- .ably employed in a, mol ratio of nitrogen to unsaturated alcohol .-charge-- of from" about i025 to about 10, and preferably from about" 0.5 to about 1.5. Higher or lower ratios of the nitrogen diluent may, however, be employed=withinthe scope 'of theinvention. K V

5 Gontact of the unsaturated alcohol andamjmonia "and/or aliphatic amine with the suitable catalyst 'is efiected at a temperature in the range of, for exampleffi'om about 300? C. to about 500 C. andpreferablyfrom about 375" C. to about 4 ing and a dehydrogenation catalyst. Suitable catalysts of this preferred class comprise those catalysts containing a. single component possessinglthe ability to: catalyze. both dehydrating and dehydrogenation reactions. Particularly preferred'catalysts, however, comprise the combina- .tion of a, dehydrating catalyst with a dehydrogenation catalyst. Suitable dehydrating catalyst .example, copper,..and its oxides.

425 C, 'Atmospliericorgsuperatmospheric pres- Q sures may suitably"beemployedi by Qsuitable catalysts comprise broadly the con- LdensationicataIyStsL suchcondensation catalysts comprise, for example, the compounds of metals contained ini the; second subgroup'to the sixth roup r the periodictable, which have a more nietailic character than arsenic. Bythe term {having a' more-inetalliccharacter than arsenic components of such catalyst combinations comprise for exampl-ethe oxides of aluminum and I fsilicon'. 1 Suitable dehydrogenation catalyst components-'to becombined therewith comprise, for 7 Examples of particularly desirable catalyst combinations comprise AlzOa-Cii, AlzOs-Cu-Ni. Of the foregoing 'catalys'tsitho'se comprising alumina in combination with copper are particularly preferred.

Theprocess of the invention may be carried out in continuous, batch or intermittent manner. Any suitabletype of reactor, or plurality of reactors, connected in series or, parallel, may be "employed.- Sui-tablereactors comprise, for example, a reaction zone of:restricted cross-sectional, area such as an externally heated tubular reactor. The catalyst within the reactor may optionally be, dilutedwith additional solid metallic material in the form of chunks, pellets, or

V diluentgases separated the like, possessing good heat 7 transmitting properties to aid in maintaining a uniform temperature; within, the reaction zone. Other types of reactors comprise those providing for the use of the catalyst in a suspended or fluidized state.

'Eflluence from the reaction zone may be passed to any'suitableproduct separating means which Y may comprise such steps as distillation, fractionation, solvent; extraction, extractive distillation,

absorption andthe like Unreacted material and from the reaction products are'recycled to the reaction zone;

is intended those metaljswhich-are precipitated from solutions of water-soluble-salts of the respective metals by the addition of metallic arsenic to said solutions; Particularly suitable compounds 'of these metals" comprise the oxides of I the metals comprised inthe second subgroup to v the fifth groupof thepetiodic table. Examplesof V such catalysts are, for example, those comprising an oxide oflaluminuml n The catalystsmaybe synthetically 'preparedpr ofnaturally occurring origin] Thus the sui't'able oxides of aluminum'comprise the aluminum-con- 1 taining catalysts synthetically prepared as well as such naturally occurring materials'as the aclikaf'fi'hefcatalysts maybe subjected to anypre treatment prior tousein the rocess to favorably affect 'thefcatalytiof activity thereof. Thus they;

' treate at; s

1 tiyated aluminafof -commerce, bauxite and the The products obtained willfvary tojsome extent" with the nature of the charge material employed; Thus, whereas the useof the lower boiling; unsaturated hydrocarbons, such as allyl a1.-

' dine or alpharpicoline.

cohol, will result in theobtaining of products comprising substantial amounts of picolines, the use of relatively hi her boiling unsaturated alcohols as the charge material willgresult' in the obtaining, of increasing amounts of falkyl' substituted pyridines having substituent alkyl groups ofmore' than one carbon atom, or having a plurality of sub'stituent alkyl groups;

The process of the" invention lends itself with particular advantage to the production of betapicoline from allyl alcohol. When employing a catalytic material having. both dehydrating and dehydrogenation properties; products are readily obtained consisting predominantly of beta-piccline and free of anysubstanti'al amountsof pyriunit oftime and per unitof weight ofv catalyst than is. possible when using as charge such'mateiri'als as a ,saturatedfalcohol, orian; aliphatic aldehyv e A particular advantage of the process oflithe invention. resides not only] i intheu'seof a -relatively but. also in the ability .to-produee the-desired 1 SQCh'fiS'QCI'OIGiHL, A further advantage reg bauxitefa'nd the 11kg maybe-subjected to: acid j of materials capable of acting both-as a dehydratsides inthe; fact that the resulting, six-membered monoheteroatomicjring compound sum as, for

example, ;the beta-picoline ,*is obtained in a mixture of reaction products f-rom which it is: generally rno r e readily"separablethan from reaction p d c s 'obtaihedywhenausing materials other assaturated alcohol,

1 treatment prior teasers increase their activity 7 L b i 4- Y j 1 Alt loughicondensa tion catalysts broadly as a cla s s maybe employed-in the process of theinventiom it has been found that substantialhci-z'n- I 5 proved results areobtained by the use ascata-lyst 7 5 1 than the a llyl alcohol, such and aliphatic aldehydes as the charge:

membered monoheteroatomic ring compounds,

but also certain other materials such as unreacted charge, a certain amount of six-membered monoheteroatomic ring compounds higher boiling than the specific one desired, some nitriles, and the like. The composition of the reaction mixture obtained will generally vary, not only in accordance with the specific materials charged, but also with the reaction conditions employed. An advantage of the invention resides, however, in the fact that the reaction mixture generally obtained enables the separation therefrom of the specifically desired six-membered heterocyclic ring compoundwith substantially greater facility than is possible in many .of the processes for the production of similar products disclosed heretofore.

Though the invention is in no wise limited to any method by which the products are separated, a suitable method for effecting such separation is the following: The products are separated into a nitrile-containing fraction and a fraction comprising the six-membered monoheteroatomic ring compounds. This is effected by fractionation. Another method of effecting such separation comprises the treatment of the reaction products with hydrochloric acid to effect the solution therein of the amines and heterocyclic six-membered ring compounds leaving the greater part of the nitriles undissolved. The undissolved nitriles are separated from the solution and the heterocyclic six-membered ring compounds are concentrated by rendering the solution alkaline and salting them out of solution. The six-membered ring compounds thus obtained are thereafter readily further separated from one another by fractionation.

In another method of effecting the separation of the desired product, the reaction mixture obtained is first fractionated to separate therefrom a fraction comprising the specific six-membered monoheteroatomic cyclic compound desired. Thereafter the six-membered cyclic compound specifically desired is separated therefrom by selective solution in hydrochloric acid.

The following examples illustrate the method of producing six-membered monoheteroatomic ring compounds in accordance with the invention.

Example I An AlzOa-Cu catalyst was prepared by immersin activated alumina in a copper nitrate solution, drying the resulting'solution and heating the mixture obtained in a hydrogen atmosphere at a temperature of about 300 C. The resulting catalyst contained an atomic ratio of aluminum to copper of 40:10.

A mixture of allyl alcohol, ammonia and nitro-. gen, containing 5 mols of ammonia and 0.75 mol of nitrogen per mol of allyl alcohol, was contacted with a portion of the above A12O3-C11 catalyst at a temperature of 400 C., atmospheric pressure. The charge was passed through the reactor at a rate of 0.34 kg. of allyl alcohol per liter of catalyst per hour. After 13 hours of continuous operation 20 mol percent of the allyl alcohol charged was converted to beta-picoline, 16.5 mol percent was converted to a nitrile-containing mixture boiling below 1 0 C. and 32.2 mol percent was converted to a mixture comprising nitriles and heterocyclic bases other than picoline having a boiling range of C. to 250 C. Only 2.5 mol percent of the charge was decomposed to carbon which Was deposited upon the catalyst.

Upon completion of the above operation, the catalyst was regenerated by heating for a period of 3 hours, at a temperature of 400 C'., in a stream of air. The regenerated catalyst was found to have regained its original activity.

Example II In a plurality of eparate operations allyl alcohol in admixture with 5 mols of ammonia and 0.75 mol of nitrogen per mol of allyl alcohol, was contacted with an alumina-copper, catalyst containing a ratio of 40 atoms of aluminum to 10 atoms of copper, at a temperature of 400 C. and atmospheric pressure. The rate of throughput in terms of kg. of allyl alcohol per liter of catalyst per hour, duration of the operation and observed results in terms of allyl alcohol converted to alphaand beta-picoline, 150 C. to 250 C. boiling mixture comprising nitriles and heterocyclic bases other than picoline and carbon is set forth in the following table:

Run No 1 2 3 4 Duration-hours 24 12 24 24 Throughput 0. 04 0.04 0. 04 0.17 M01 percent allyl alcohol converted to:

Alpha-picoline 0 0 0 Beta-picoline 16. 8 27 20. 3 27 150 to 250 C. boiling rang 22.0 33. 5 25. 5 32 Carbon 5. 3 4 2. 8 4

essentially of an oxide of alumina in admixture with copper, at a temperature of from about 300 C. to about 500 C.

3. A process for the production of 3-methyl pyridine which comprises passing a mixture of allyl alcohol and ammonia over a catalyst consisting essentially of activated alumina and copper within the temperature range of about 300 C. to 500 C.

HAN HOOG. WILLEM FREDERIK ENGEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES J. 'fur Prat. Chemie, 1924, Band 107, pp. 123-124.

Ser. No. 387, 06, stitz (A. P. (1.). published. July 13, 1943. 

1. A PROCESS FOR THE PRODUCTION OF BETA-PICOLINE WHICH COMPRISES REACTING ALLYL ALCOHOL WITH AMMONIA IN THE PRESENCE OF A MOL EXCESS OF AMMONIA AND A CATALYST CONSISTING ESSENTIALLY OF ALUMINA AND COPPER AT A TEMPERATURE OF FROM ABOUT 300* C. TO ABOUT 500* C. 